JavaScript Browser Detection

Detecting your viewer's browser

Browser detection allows you to find out what browser your viewer is using, and then perform a script based on it-- or just to send a friendly message to those with your favorite browser.

There are two objects often used for this, the navigator.appName and navigator.appVersion objects. The first one returns the name of the browser, the second returns the version of the browser.
If the browser is Netscape, navigator.appName returns the string "Netscape". If it is Internet Explorer, it returns the string "Microsoft Internet Explorer". Using just this, you could make a script to alert people as to what browser they are using (just to bug them). Like this:

You can do the same thing with the navigator.appVersion, except you will most likely want to grab just the integer from the version information (2,3,4, etc.). To do this, we use the parseInt() function:

var browserVer=parseInt(navigator.appVersion); 

Now, it returns only the integer value and not something like version 4.51. It just sends back 4 in that case. Thus, we could alert viewers as to whether their browser is new enough for us or not:

you can use both objects to be more exact. You could look for a certain set of browsers and only if they are above a certain version: